Accelerated silicosis in workers exposed to agate dust in Guangzhou, China

Background: An investigation of a small private agate mill was prompted by an agate worker who presented with silicosis in Guangzhou, China, in December 1998. Methods: The work processes and records of dust measurements of the mill were examined. The mean total dust concentrations ranged from 3.0 to 9.9 mg/m³; 86-88% of the particles' diameter was smaller than 5.0 gm. Free SiO₂ content from agate samples was measured. Occupational history was obtained and X-ray chest and lung function was carried out. Results: Free SiO₂ content of the agate was 90.5%. Thirty-two men involved in processing agate stone were examined. The mean (± SD) age was 29.8 (± 4.9) years and the mean (± SD) duration of exposure was 3.5 (± 1.7) years. Fifteen cases (47%) were diagnosed as accelerated silicosis. Up to September 1999, three had died from respiratory failure and five were in critical condition. Conclusion: Silicosis is an important problem in primitive work environments.